Re: GBlist: cellulose insulation; live roofs; TJIs; stem roofs and foundations,

Mike O'Brien (
Fri, 14 Feb 97 16:22 PST

Hi, Robert--

Some quickie thoughts--

>1) Cellulose Insulation - How do you insure that there is an air space
>for ventilation if one blows the cellulose in the cavity? Is an air
>space necessary? How do you design to insure an air space?

Assuming you are talking about the attic cavity, the best option is to
install continuous vents that run along the eaves and at the ridge,
together with baffling inside the eave vent that prevents outdoor air from
blowing insulation away from the edges of the attic floor. The insulation
should extend over the exterior walls. Together with a light colored roof
the vents will help keep the place a little cooler in summer. Also
recommended is to seal air leaks in attic floor (light fixtures, plumbing
vents, wiring, fan boxes, even drywall-to-top plates) so moisture-laden air
doesn't get transported into the attic from inside the occupied space.
Install a moisture barrier (poly + gravel base course) under the slab floor
to keep ground water from wicking through the concrete and ending up in the
attic. If you install a radiant floor the underslab insulation will also
act like a moisture barrier.

>2) TJI - The maximize span of roof joists will be 24 feet. We are
>considering using TJIs? Are there any other products that are
>recommmended? What are they? Who are the suppliers. Note we are
>considering installing a live roof, we need a product that can
>accomodate the load of a live roof?

If you buy your trusses from Truss Joist McMillan they will provide the
engineering for the design loads your plan, snow loads, Utah code etc.
calls for, and recommend the trusses + installation, or they will at least
send you their excellent design materials. Other companies may also do

>3) Live Roof _ We are debating the pros and cons of installing a live
>roof. We would like to discuss with anyone who has experience building
>as well as living with a live roof what are the pros and cons. We are
>especially interested in talking with someone who lives in a desert
>environment such as Moab

What's a live roof? Does your code official know about it?

>4) Stem Wall and Foundation - We are considerng using Faswall blocks
>and we are wondering whether there are other products we should
>consider. We would like to minimize the use of concrete.

What's wrong with concrete?

>5) Used Cement Mixer - We would like to buy a used gas powered 4 to 6
>cubic foot cement mixer. If you live within 200 miles more or less from
>Moab, we would like to talk with you.

Good luck!!

>6) Heating and Cooling Equipment recommendations - while we will be
>designing the building in order to minimize the need for auxillary
>heating and cooling systems we anticipate the need for auxillary
>systems. Are there particular manufacturers and models that people
>recommend, why and how do we get information?

Maybe someone of the GB list would be willing to run an energy analysis of
the building to help determine the heating and cooling loads, and give you
an idea how big a system you'll need, if you will post the thermal envelope
specs. What fuel do you prefer? Do you want to be able to circulate and
filter air as part of the heating and cooling, or will there be a separate
ventilation system?

>7) Insulation - Is there other insulation other than cellulose that
>people would recommend for the ceiling/roof. We are looking for items
>which are cost effective and easy to install. We are planning to have
>R-40 to R 50 insulation for the ceiling. We are also looking for
>recommendations for rigid Board insulation.

Cellulose is a good blown-in material--check the weight; at R-50 might need
5/8" ceiling drywall to carry the load. Can you even get other types in
Moab? If so rock wool is good insulation and made from recycled slag.
Fiberglass is OK also. You'll want to check out the debate over cellulose
and fire safety vs. fiberglass and cancer.

>8) We are also researching types of windows and doors. Are there
>particular manufacturers people like or dislike.

In your vinyls,I like Milgard products, and they now have a Heat Mirror
window. In your woods, Pozzi makes pretty good windows for the money. If
you are going passive solar, I don't know of any windows that work well as
a roof--I've given up on overhead glazing, except for skylights.

Best wishes!!


>Thank you,
>Robert Seelig
>Moab, Utah
>This greenbuilding dialogue is sponsored by Oikos (
>and Environmental Building News ( For instructions
>send e-mail to

O'Brien & Associates
Environmental Building Consultants
Portland General Electric Earth Smart program
Earth-Wise Builders

This greenbuilding dialogue is sponsored by Oikos (
and Environmental Building News ( For instructions
send e-mail to